Experimental and numerical study on hydrodynamic characteristics of a bottom-hinged pitching flap breakwater under regular waves.

A bottom-hinged flap breakwater is proposed for the wave attenuation and coastal protection. A series of laboratory experiments and a CFD numerical model were conducted to investigate the hydrodynamic characteristics in regular waves. The hydrodynamic coefficients, dimensionless maximum point pressure and average pitching amplitude of flap were examined with the parameters of incident waves and flap property. As the incident wave steepness increased, the wave reflection coefficient K r , wave transmission coefficient K t , dimensionless maximum point pressure p max / ρ w gh , and average pitching amplitude of flap θ a increased for a given wave period; however, the wave dissipation coefficient K d decreased. As the flap relative height increased, K r and θ a increased for a given wave period; whereas, K t decreased. Furthermore, as the flap density ratio increased, K r , p max / ρ w gh , and fitted K d increased; however, K t and θ a decreased. As the equivalent damping coefficient ratio increased, K r and p max / ρ w gh increased; however, K t and θ a decreased. Additionally, a series of dimensionless parameters of incident waves and flap property were used to derive formulas for K r , K t and K d , which were validated using the related data. • A bottom-hinged pitching flap breakwater is proposed for the wave attenuation and coastal protection. • Laboratory experiments are conducted to study the hydrodynamic characteristics of the device in regular waves. • A numerical model is used to simulate the pitching motion of the bottom-hinged flap. • The hydrodynamic coefficients and flap average pitching amplitude are examined with the wave and flap parameters. • The prediction formulas are conducted to assess the hydrodynamic coefficients of the flap with an acceptable accuracy. [ABSTRACT FROM AUTHOR]